An introduction to the EZSim reservoir simulation software

The New Product

EZSim is an EOS based general purpose compositional reservoir simulator with fully implicit formulation. It allows any components appear and stay in any fluid phases (aqueous, oilec and vapour ).

In other words, it uses three-phase flash to allow light hydrocarbon components dissolved in aqueous phase, and water dissolved in oilec phase and vapour phase. Separator(s) with two or three-phase flash is used to separate all fluid phases at separator or surface condition.

It can be simplified to the conventional or traditional black oil, compositional and thermal modules. It also can be expanded to fully EOS based thermal simulator. EZSim is designed for reservoir engineers to conduct simple and quick researches or studies on recovery mechanistic, history match and forecasts.

Main features within current model:

Features Description
Keyword input: Free format, can convert eclipse keywords or data set(partially) to EZSim's format
Unit: Field or SSI (metric)
Run-time dimensioning: Cover most arrays
Grid: Radial, Cartesian Grids and Corner point Geometry with Non-neighbor connections
PVT: Black oil, Compositional and thermal modules
Fluids Type: Oil-Water, Gas-water, Oil-Water-Gas
Recovery Mechanisms: Primary, Water and Gas floods, WAG, Steam Cycling and flood.
Reservoir type: Single Porosity or Dual Permeability (no dual porosity module)
Model Initialization: User specified or use vertical equilibrium for block-center or corner-point geometry.
Scal: Three phase relative permeabilities with oil phase modeled by Stone 1 and 2, also handle 2 or 3-point scaling and temperature depended end-points.
Well Type: Vertical, slant or horizontal.

Benchmarks:

The accuracy, speed, and stability of EZSim have been benchmarked with well known SPE papers: SPE 1,2,3,4,5,6,7,9,10 as shown in table 1.

Table 1

Case Description
SPE_1 black oil model, gas drive
SPE_2 black oil model, radial grid, water coning
SPE_3 compositional model, gas recycling
SPE_4 thermal model, steam cycling, flooding
SPE_5 Original case: compositional model, WAG cycling
SPE_5 Modified case: compositional model, gas drive in finer cell size. One commercial simulator has serious convergence problems and the calculation of Oil-Production-Rate is weird; EZSim's result is consistent with others. And more importantly, on the same computer ( one CPU), Third party reported that EZSim's run time is much less than others
SPE_6 black oil dual permeability model, 2D-Cross section
SPE_7 black oil model, water drive with Horizontal Wells
SPE_9 black oil model, water drive with tilted reservoir
SPE_10 black oil model, Two phase water and oil. coarsen grids: 30x55X85 and 10x20x10

The comparison results with other commercial simulators are shown on Figures 1 to ??

The comparison results with other commercial simulators are shown on Figures 1 to ??

Comparison results

SPE_1
FPR FGOR FOPR
SPE_2
FPR FGOR FOPR
SPE_3
FOPR FWCT FGOR
SPE_4
FOPT FOPR FPR
SPE_5
FOPR FOPT
SPE_6
FPR FWCT FOPR
SPE_7
FWCT FOPR
SPE_9
FOPR FWCT FGOR
SPE_10 with edited grid dimension
FOPR FWCT FPR

Other examples:

  • Based on SPE 5, grid dimension effect, compared with other commercial simulator
SPE_5 with grid dimension 20X20X6
FPR FOPR FGOR
SPE_5 with grid dimension 10X10X6
FOPT FOPR
  • End point scaling, compared with one commercial simulator
FOPR Comparison FGOR Comparison FPR Comparison
FOPR FGOR FPR
  • Corner Point grid
Corner Point grid Corner Point grid FOPR & FOPT
Corner Point grid Corner Point grid FOPR

Advanced examples:

  • Based on SPE 3, gas drive with 3 phase (water, oil, gas) EOS flash and 3 phase separator
Mole fraction of C1 in water Mole fraction of water in gas
mfw_c1 mfg_wate
  • Based on SPE 5, CO2 drive with 3 phase (water, oil, gas) EOS flash and 3 phase separator, compared with one commercial simulator
FOPR Comparison FGPR Comparison
FOPR FGPR
Mole fraction of C1 in water Mole fraction of CO2 in water
mfw_c1 mfw_co2
  • Steam drive with 3 phase (water, oil, gas) EOS flash and 3 phase separator
Temperature Mole fraction of C1 in water Mole fraction of water in oil
temp mfw_c1 mfo_h2o

Many examples or templates are available by private request through email.